It is desirable to be able to transmit confidential and personal information over unsecured public computer networks, such as the internet. To allow this, it is necessary to provide a secure registration system, which allows an individual user to have confidence that personal information transmitted over the network will remain confidential. Conversely, a service provider may wish to ensure that only some computer users are able to access specific information.
U.S. Pat. No. 5,784,463 describes a system in which a computer system is secured against authorized access, while date exchanged by a user with the computer system is encrypted when it is sent over the public network.
More specifically, U.S. Pat. No. 5,784,463 describes the use of an authentication token, which may be a hardware device or which may be a software module, which allows the user to authenticate himself to the remote computer. In this prior art system, shared secret keys provide mutual authentication between the two users. The shared secret keys are generated only at the time of registration, and are distributed using a public key/private key cryptographic system.
This system has the disadvantage that, before a computer user can take part in secure online transactions using the described system, he must obtain a separate authentication token. Further there is a cost associated with the distribution of such tokens, either to pay for the additional hardware, or to supply information for the software module.